U.S. patent application number 15/955228 was filed with the patent office on 2018-12-06 for speaker.
This patent application is currently assigned to ALPINE ELECTRONICS, INC.. The applicant listed for this patent is ALPINE ELECTRONICS, INC.. Invention is credited to Masaru Yamagami.
Application Number | 20180352336 15/955228 |
Document ID | / |
Family ID | 62486484 |
Filed Date | 2018-12-06 |
United States Patent
Application |
20180352336 |
Kind Code |
A1 |
Yamagami; Masaru |
December 6, 2018 |
SPEAKER
Abstract
A cap member is attached to an opening end portion of a bobbin
on which a voice coil is wound. The cap member includes a bobbin
reinforcement portion including a cylindrical portion and a bottom
surface portion. The cylindrical portion opposes an inner surface
of the bobbin, and the cylindrical portion and the inner surface of
the bobbin are fixed to each other in at least a vibration plate
fixed portion and a damper member fixed portion.
Inventors: |
Yamagami; Masaru;
(Iwaki-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALPINE ELECTRONICS, INC. |
Tokyo |
|
JP |
|
|
Assignee: |
ALPINE ELECTRONICS, INC.
Tokyo
JP
|
Family ID: |
62486484 |
Appl. No.: |
15/955228 |
Filed: |
April 17, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04R 9/025 20130101;
H04R 9/06 20130101; H04R 7/12 20130101; H04R 9/043 20130101; H04R
1/288 20130101; H04R 31/006 20130101; H04R 7/18 20130101; H04R
2400/11 20130101; H04R 7/127 20130101 |
International
Class: |
H04R 9/06 20060101
H04R009/06; H04R 7/18 20060101 H04R007/18; H04R 9/02 20060101
H04R009/02; H04R 7/12 20060101 H04R007/12; H04R 1/28 20060101
H04R001/28 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 2017 |
JP |
2017-109642 |
Claims
1. A speaker comprising: a magnetic circuit portion supported by a
frame portion and forming a magnetic gap; a hollow bobbin; a voice
coil wound on the bobbin and located inside the magnetic gap; and a
vibration plate disposed between the frame portion and the bobbin,
wherein the vibration plate is fixed to a vibration plate fixed
portion located at an outer surface of an intermediate portion
spaced away from an opening end portion of the bobbin, and wherein
a cap member is attached to the opening end portion of the bobbin,
and the cap member is provided with a bobbin reinforcement portion
extending from the opening end portion toward the intermediate
portion inside the bobbin and opposing the vibration plate fixed
portion or the vicinity of the vibration plate fixed portion.
2. The speaker according to claim 1, wherein the bobbin
reinforcement portion is fixed to the bobbin in at least an inner
surface of the vibration plate fixed portion.
3. The speaker according to claim 1, wherein the bobbin
reinforcement portion includes a cylindrical portion opposing an
inner surface of the bobbin and a bottom surface portion located at
an end portion of the cylindrical portion directed toward the
inside of the bobbin, and the bottom surface portion opposes the
vibration plate fixed portion or the vicinity thereof.
4. The speaker according to claim 1, wherein the vibration plate
fixed portion is located at a position spaced away from the opening
end portion of the bobbin.
5. The speaker according to claim 1, wherein the cap member is
provided with an outer support portion extending toward an outer
peripheral side in relation to the opening end portion of the
bobbin, and the outer support portion is fixed to the vibration
plate.
6. The speaker according to claim 1, wherein a damper member is
provided between the frame portion and the bobbin, and the bobbin
reinforcement portion also opposes a fixed portion of the damper
member in the bobbin.
7. A speaker comprising: a magnetic circuit portion supported by a
frame portion and forming a magnetic gap; a hollow bobbin having an
opening end portion; a voice coil wound on the bobbin and located
inside the magnetic gap, where an upper end portion of the voice
coil is spaced a distance L0 from the opening end portion of the
bobbin; and a vibration plate disposed between the frame portion
and the bobbin, wherein the vibration plate is fixed to a vibration
plate fixed portion located at an outer surface of an intermediate
portion spaced away from the opening end portion of the bobbin at a
distance L1 that is between 1/3 and 2/3 of the distance L0, and
wherein a cap member is attached to the opening end portion of the
bobbin, and the cap member is provided with a bobbin reinforcement
portion extending from the opening end portion toward the
intermediate portion inside the bobbin and opposing the vibration
plate fixed portion or the vicinity of the vibration plate fixed
portion.
8. The speaker according to claim 1, wherein the bobbin
reinforcement portion is fixed to the bobbin in at least an inner
surface of the vibration plate fixed portion.
9. The speaker according to claim 1, wherein the bobbin
reinforcement portion includes a cylindrical portion opposing an
inner surface of the bobbin and a bottom surface portion located at
an end portion of the cylindrical portion directed toward the
inside of the bobbin, and the bottom surface portion opposes the
vibration plate fixed portion or the vicinity thereof.
10. The speaker according to claim 1, wherein the vibration plate
fixed portion is located at a position spaced away from the opening
end portion of the bobbin.
11. The speaker according to claim 1, wherein the cap member is
provided with an outer support portion extending toward an outer
peripheral side in relation to the opening end portion of the
bobbin, and the outer support portion is fixed to the vibration
plate.
12. The speaker according to claim 1, wherein a damper member is
provided between the frame portion and the bobbin, and the bobbin
reinforcement portion also opposes a fixed portion of the damper
member in the bobbin.
13. A speaker comprising: a magnetic circuit portion supported by a
frame portion and forming a magnetic gap; a hollow bobbin; a voice
coil wound on the bobbin and located inside the magnetic gap; and a
vibration plate disposed between the frame portion and the bobbin,
wherein the vibration plate is fixed to a vibration plate fixed
portion located at an outer surface of an intermediate portion
spaced away from an opening end portion of the bobbin, and wherein
a cap member is attached to the opening end portion of the bobbin,
the cap member is provided with a bobbin reinforcement portion
extending from the opening end portion toward the intermediate
portion inside the bobbin and opposing the vibration plate fixed
portion or the vicinity of the vibration plate fixed portion, and
the cap member includes a central support column and a plurality of
fins between the central support column and the bobbin
reinforcement portion of the cap member.
14. The speaker according to claim 1, wherein the bobbin
reinforcement portion is fixed to the bobbin in at least an inner
surface of the vibration plate fixed portion.
15. The speaker according to claim 1, wherein the bobbin
reinforcement portion includes a cylindrical portion opposing an
inner surface of the bobbin and a bottom surface portion located at
an end portion of the cylindrical portion directed toward the
inside of the bobbin, and the bottom surface portion opposes the
vibration plate fixed portion or the vicinity thereof.
16. The speaker according to claim 1, wherein the vibration plate
fixed portion is located at a position spaced away from the opening
end portion of the bobbin.
17. The speaker according to claim 1, wherein the cap member is
provided with an outer support portion extending toward an outer
peripheral side in relation to the opening end portion of the
bobbin, and the outer support portion is fixed to the vibration
plate.
18. The speaker according to claim 1, wherein a damper member is
provided between the frame portion and the bobbin, and the bobbin
reinforcement portion also opposes a fixed portion of the damper
member in the bobbin.
Description
RELATED APPLICATION
[0001] The present application claims priority to Japanese Patent
Application Number 2017-109642, filed Jun. 2, 2017, the entirety of
which is hereby incorporated by reference.
BACKGROUND
1. Field of the Invention
[0002] The present invention relates to a speaker in which an inner
peripheral edge of a vibration plate is fixed to a bobbin having a
voice coil wound thereon, and the bobbin and the vibration plate
are driven by a current flowing in the voice coil and a magnetic
field of a magnetic circuit portion.
2. Description of the Related Art
[0003] In a structure of a conventional speaker, a voice coil is
wound on a bobbin and magnetic energy of a magnetic circuit portion
is transmitted to the voice coil so that the magnetic energy is
converted into kinetic energy of the voice coil and the bobbin.
Further, a vibration is transmitted from the bobbin to a vibration
plate, and sound energy is emitted into a space from the vibration
plate. In this speaker, when the rigidity of the bobbin
transmitting the kinetic energy is low, distortion and extra
vibration are likely to occur in the bobbin. Particularly, since
stress easily concentrates on a vibration plate fixed portion in
the bobbin, the bobbin of the vibration plate fixed portion is
easily deformed. As a result, a decrease in sound pressure and
nonlinear distortion are likely to occur in the sound emitted from
the vibration plate.
[0004] An approach of forming a part or the entirety of the bobbin
of a metal material such as titanium or aluminum has been
considered in order to improve the rigidity of the bobbin. However,
in this approach, since the mass of the bobbin increases too much,
a decrease in sound pressure cannot be solved effectively. Further,
since the metal material is used, manufacturing cost increases.
[0005] A structure of a conventional speaker is shown in JP
2005-252923 A. In this speaker, a cone-shaped vibration plate is
fixed to an outer surface of an intermediate portion away from an
opening end portion of a bobbin on which a voice coil is wound, and
a dust cap is fixed to the opening end portion of the bobbin.
[0006] In the speaker described in JP 2005-252923 A, since the dust
cap is fixed to the opening end portion of the bobbin, the opening
end portion of the bobbin can be reinforced. However, the
intermediate portion of the bobbin to which the vibration plate is
fixed is not reinforced at all. When the intermediate portion of
the bobbin to which the vibration plate is fixed is not reinforced,
distortion tends to occur in the bobbin and the vibration plate
during a sound generation driving operation. Accordingly, there is
a concern that sound quality may be deteriorated and a coil wire of
the voice coil may be disconnected.
SUMMARY
[0007] The present invention has been made to address the
above-described conventional problems, and an object of the
invention is to provide a speaker capable of effectively
reinforcing a bobbin and preventing deterioration of sound quality
and disconnection of a coil wire.
[0008] According to an embodiment of the invention, there is
provided a speaker including: a magnetic circuit portion supported
by a frame portion and forming a magnetic gap; a hollow bobbin; a
voice coil wound on the bobbin and located inside the magnetic gap;
and a vibration plate disposed between the frame portion and the
bobbin, in which the vibration plate is fixed to a vibration plate
fixed portion located at an outer surface of an intermediate
portion spaced away from an opening end portion of the bobbin, and
a cap member is attached to the opening end portion of the bobbin
and the cap member is provided with a bobbin reinforcement portion
extending from the opening end portion toward the intermediate
portion inside the bobbin and opposing the vibration plate fixed
portion or opposing the vicinity of the vibration plate fixed
portion.
[0009] In the speaker of the embodiment of the invention, it is
preferable that the bobbin reinforcement portion is fixed to the
bobbin in at least an inner surface of the vibration plate fixed
portion.
[0010] In the speaker of the embodiment of the invention, it is
preferable that the bobbin reinforcement portion includes a
cylindrical portion opposing an inner surface of the bobbin and a
bottom surface portion located at an end portion directed toward
the inside of the bobbin of the cylindrical portion, and the bottom
surface portion opposes the vibration plate fixed portion or the
vicinity thereof.
[0011] In the speaker of the embodiment of the invention, the
vibration plate fixed portion may be located at a position away
from the opening end portion of the bobbin.
[0012] In the speaker of the embodiment of the invention, it is
more preferable that the cap member is provided with an outer
support portion extending toward an outer peripheral side in
relation to the opening end portion of the bobbin, and the outer
support portion is fixed to the vibration plate.
[0013] In the speaker of the embodiment of the invention, it is
preferable that a damper member is provided between the frame
portion and the bobbin, and the bobbin reinforcement portion also
opposes a fixed portion of the damper member in the bobbin.
[0014] According to the speaker of the embodiment of the invention,
many parts of the bobbin can be reinforced by the bobbin
reinforcement portion of the cap, and also the vibration plate
fixed portion of the bobbin is reinforced. Accordingly, it is
possible to improve the rigidity of the bobbin and to improve sound
characteristics.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a perspective view illustrating a speaker of a
first embodiment of the invention in a state in which a sound
generation side faces upward;
[0016] FIG. 2 is a longitudinal sectional view of the speaker of
the first embodiment illustrated in FIG. 1;
[0017] FIG. 3 is a partially enlarged cross-sectional view of a
part of FIG. 2;
[0018] FIG. 4 is a partially exploded perspective view illustrating
a part of a structure of the speaker of the first embodiment
illustrated in FIG. 1 and including a partial cross-section;
[0019] FIG. 5 is a partially exploded perspective view illustrating
a part of a modified example of the speaker of the first embodiment
of the invention;
[0020] FIG. 6 is a partially cross-sectional view illustrating the
speaker of the modified example illustrated in FIG. 5; and
[0021] FIG. 7 is a half cross-sectional view illustrating a part of
a counter drive type speaker according to a second embodiment of
the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] A speaker 1 of a first embodiment of the invention
illustrated in FIGS. 1 to 4 includes a frame portion 2. For
example, the frame portion 2 is formed by die-casting light metal
or is formed by press forming a steel plate. As illustrated in FIG.
2, the frame portion 2 includes a magnetic circuit portion support
portion 2a, a damper support portion 2b, and a vibration plate
support portion 2c. The frame portion 2 may be integrally formed as
a whole or may be formed such that one of the magnetic circuit
portion support portion 2a, the damper support portion 2b, and the
vibration plate support portion 2c is formed separately from the
other parts and these parts are combined and fixed to each
other.
[0023] A magnetic circuit portion 3 is fixed to the magnetic
circuit portion support portion 2a of the frame portion 2. As
illustrated in FIG. 2, the magnetic circuit portion 3 includes a
pole yoke 4 which is located at the center, a lower yoke 5 which is
fixed to the lower side (the side of Z2) of the pole yoke 4, and an
opposing yoke 6 which opposes the upper side (the side of Z1) of
the lower yoke 5, and a magnet 7 is fixed to be interposed between
the lower yoke 5 and the opposing yoke 6. The magnet 7 is an
annular permanent magnet and the pole yoke 4 is located inside a
center hole of the magnet 7. The upper surface (the surface on the
side of Z1) and the lower surface (the surface on the side of Z2)
of the magnet 7 are magnetized to different magnetic poles. A
magnetic gap G is formed in an opposing portion between the pole
yoke 4 and the yoke 6.
[0024] The speaker 1 is provided with a bobbin 11. The bobbin 11 is
a cylindrical body of which a cross-section is a true circle and
which is hollow. Alternatively, the cross-section of the bobbin 11
may be elliptical, oval, or polygonal. The bobbin 11 is made of
paper or a synthetic material of paper and synthetic resin.
Alternatively, the bobbin may be made of synthetic resin material.
That is, the bobbin 11 is made of at least one of a paper material
and a synthetic resin material and does not include a metal
material. For that reason, the bobbin 11 can be low in weight. The
bobbin 11 has an opening end portion 11c formed at an end portion
in the direction Z1.
[0025] As illustrated in FIGS. 2 and 4, a voice coil 12 is provided
at the lower side (the side of Z2) of the bobbin 11. The voice coil
12 is formed by winding a coated wire on the bobbin 11. As
illustrated in FIG. 2, a portion of the bobbin 11 on which the
voice coil 12 is wound is located inside the magnetic gap G of the
magnetic circuit portion 3.
[0026] As illustrated in FIG. 2, a vibration plate 15 is provided
between the bobbin 11 and the vibration plate support portion 2c of
the frame portion 2. The vibration plate 15 has a so-called cone
shape and is made of, for example, paper or a synthetic material of
paper and synthetic resin. Alternatively, the vibration plate 15
may be made of a synthetic resin material. That is, the vibration
plate 15 is made of at least one of a paper material and a
synthetic resin material.
[0027] As illustrated in FIG. 2, an outer peripheral support member
18 is provided between the vibration plate support portion 2c and
an outer peripheral edge 15a of the vibration plate 15. The outer
peripheral support member 18 has a curved cross-section and is
deformable with the vibration of the vibration plate 15. As
illustrated in the enlarged view of FIG. 3, an inner peripheral
edge 15b of the vibration plate 15 is fixed to an outer surface 11a
of the bobbin 11, such as by adhesive. In particular, the inner
peripheral edge 15b is fixed to the outer surface of the bobbin 11
at an intermediate portion spaced away from the opening end portion
11c of the bobbin 11 in the direction Z2. In the bobbin 11, a
portion to which the vibration plate 15 is fixed is a vibration
plate fixed portion (i) and a portion in which the vibration plate
fixed portion (i) exists is an intermediate portion spaced away
from the opening end portion 11c by a distance L1.
[0028] As illustrated in FIG. 2, a damper member 16 is provided
between the bobbin 11 and the damper support portion 2b of the
frame portion 2. FIG. 3 is an enlarged cross-sectional view of the
damper member 16, and FIG. 4 is a perspective view of a part of the
damper member 16.
[0029] The damper member 16 is made of, for example, a woven fabric
impregnated with resin or the like. The damper member 16 is
corrugated and its cross-section is corrugated. As illustrated in
FIG. 2, an outer peripheral edge 16a of the damper member 16 is
fixed to the damper support portion 2b of the frame portion 2. As
illustrated in the enlarged view of FIG. 3, the inner peripheral
edge 16b of the damper member 16 is fixed to the outer surface 11a
of the bobbin 11 by adhering. In the bobbin 11, a portion to which
the inner peripheral edge 16b of the damper member 16 is fixed is a
damper member fixed portion (ii).
[0030] As illustrated in FIG. 3, the vibration plate fixed portion
(i) and the damper member fixed portion (ii) of the bobbin 11 are
very close to each other. When a portion of a distance L0 from the
upper opening end portion 11c of the bobbin 11 to the upper end
portion 12a of the voice coil 12 is set as a main body 13 of the
bobbin 11, the vibration plate fixed portion (i) and the damper
member fixed portion (ii) are located at the intermediate portion
of the main body 13. That is, a distance L1 from the opening end
portion 11c of the bobbin 11 to the vibration plate fixed portion
(i) is 1/3 or more and 2/3 or less of the length dimension L0 of
the main body 13. Further, a distance L2 between the vibration
plate fixed portion (i) and the damper member fixed portion (ii) in
the vertical direction is 1/5 or less and preferably 1/10 or less
of the distance L0.
[0031] As illustrated in FIGS. 2 and 3, a cap member 20 is attached
to the bobbin 11. The cap member 20 is fitted into the hollow inner
portion of the bobbin 11 from the opening end portion 11c of the
bobbin 11. The cap member 20 is formed by injection-molding
synthetic resin and is integrally formed as a whole or is formed
such that a plurality of parts formed by injection-molding
synthetic resin are combined with each other.
[0032] As illustrated in the enlarged view of FIG. 3, the cap
member 20 includes a cylindrical portion 22 which extends downward
toward the intermediate portion from the opening end portion 11c
inside the hollow inner portion of the bobbin 11. A bottom surface
portion 23 is provided at an end portion 22a (an end portion on the
side of Z2) facing the inside of the bobbin 11 in the cylindrical
portion 22. The end portion 22a of the cylindrical portion 22 is
completely covered by the bottom surface portion 23 and is able to
prevent dust or liquid from intruding into the magnetic circuit
portion 3 from a space on the side of Z1. Here, an opening may be
formed in a part of the bottom surface portion 23. In the cap
member 20, a bobbin reinforcement portion 21 is formed by the
cylindrical portion 22 and the bottom surface portion 23.
[0033] The cylindrical portion 22 contacts the inner surface 11b of
the bobbin 11 or opposes the inner surface 11b through a narrow
gap. The outer peripheral surface of the cylindrical portion 22 and
the inner surface 11b of the bobbin 11 are fixed to each other by
an adhesive in at least a part thereof. It is preferable that the
outer peripheral surface of the cylindrical portion 22 and the
inner surface 11b of the bobbin 11 are fixed to each other by an
adhesive in an area covering at least the vibration plate fixed
portion (i) and the damper member fixed portion (ii), for example,
a height range of L3 illustrated in FIG. 3. It is further
preferable that the inner surface 11b and the outer surface of the
cylindrical portion 22 adhere to each other in the entire area of
the range of the height L4 in which the bobbin 11 and the
cylindrical portion 22 face each other.
[0034] The height dimension L4 of the area in which the inner
surface 11b of the bobbin 11 and the outer peripheral surface of
the cylindrical portion 22 oppose each other is preferably or more
and further preferably 1/2 or more of the height dimension L0 from
the opening end portion 11c of the bobbin 11 to the upper end
portion 12a of the voice coil 12. When the height dimension is
provided in the above-described range, the bobbin 11 can be
effectively reinforced.
[0035] Further, the end portion 22a of the cylindrical portion 22
is preferably located at the lower side (the side of Z2) in
relation to the vibration plate fixed portion (i) and is further
preferably located at the lower side (the side of Z2) in relation
to both the vibration plate fixed portion (i) and the damper member
fixed portion (ii). Here, when the height dimension L4 is or more
of the height dimension L0, the end portion 22a of the cylindrical
portion 22 may be located at the slightly upper side (the side of
Z1) in relation to the vibration plate fixed portion (i) and the
damper member fixed portion (ii). That is, the end portion 22a of
the cylindrical portion 22 may be located in the vicinity of at
least the vibration plate fixed portion (i) and the damper member
fixed portion (ii).
[0036] The cap member 20 is provided with an outer support portion
24 which further extends to the outer peripheral side from the
opening end portion 11c of the bobbin 11, and the peripheral edge
portion 24a of the outer support portion 24 is fixed to a surface
facing the side of Z1 in the vibration plate 15, such as by
adhesive.
[0037] In the speaker 1 of the first embodiment, when a voice
current flows to the voice coil 12, an electromagnetic force
(magnetic energy) caused by the voice current and the magnetic
field traversing the magnetic gap G of the magnetic circuit portion
3 is converted into kinetic energy in the Z1-Z2 direction of the
voice coil 12. This kinetic energy is transmitted from the bobbin
11 to the vibration plate 15 so that the vibration plate 15 is
vibrated and sound energy is emitted to a space.
[0038] As illustrated in FIG. 3, the bobbin 11 is reinforced by the
bobbin reinforcement portion 21 of the cap member 20 in the range
of the height L4 of preferably or more of the height dimension L0
from the opening end portion 11c of the bobbin 11 to the upper end
portion 12a of the voice coil 12. For that reason, it is possible
to improve the rigidity of the bobbin 11 that transmits the kinetic
energy. Here, since the bobbin 11 is made of at least one of a
paper material and a synthetic resin material, it is possible to
reduce the mass of the bobbin 11. Since the bobbin 11 is
lightweight and has high rigidity, the bobbin 11 can efficiently
transmit the kinetic energy applied to the voice coil 12 to the
vibration plate 15 without attenuating or distorting the kinetic
energy. As a result, it is possible to prevent a decrease in sound
pressure and to easily maintain linearity of sound.
[0039] Further, since a resistance force is applied from the
vibration plate 15 and the damper member 16 when the bobbin 11
moves in the Z1-Z2 direction, stress easily concentrates on the
vibration plate fixed portion (i) and the damper member fixed
portion (ii) of the bobbin 11. Particularly, since the vibration
plate 15 has a large area and high rigidity, stress easily
concentrates on the vibration plate fixed portion (i) in the bobbin
11. Here, as illustrated in FIG. 3, when the cylindrical portion 22
of the bobbin reinforcement portion 21 of the cap member 20 is
fixed to the inner surface 11b of the bobbin 11 by adhering in an
opposing state in the vibration plate fixed portion (i) and the
damper member fixed portion (ii), it is possible to easily suppress
deformation due to the concentration of stress in the vibration
plate fixed portion (i) and the damper member fixed portion
(ii).
[0040] Further, the bobbin reinforcement portion 21 of the cap
member 20 includes the bottom surface portion 23, but when the
bottom surface portion 23 is disposed in the vicinity of the
vibration plate fixed portion (i) and the damper member fixed
portion (ii) of the bobbin 11, the rigidity of the bobbin 11 in the
vibration plate fixed portion (i) and the damper member fixed
portion (ii) can be improved. Accordingly, it is possible to
suppress deformation in the bobbin crushing direction and to
maintain high kinetic energy transmission efficiency due to the
bobbin 11.
[0041] Further, the coil wire connected to the voice coil 12 is
laid from the bobbin 11 toward the vibration plate 15, but since
the repeated bending of the coil wire is suppressed due to the
reinforcement of the bobbin 11, a disconnection of the coil wire
can be prevented.
[0042] Further, the cap member 20 includes the outer support
portion 24, and the peripheral edge portion 24a of the outer
support portion 24 is fixed to the vibration plate 15. Since the
bobbin 11 can be reinforced by the cap member 20 and the vibration
plate 15 can be also supported, it is possible to prevent
distortion and unnecessary vibration in the bobbin 11, the inner
peripheral portion of the vibration plate 15, and the like and to
further easily attenuate a sound effect.
[0043] FIGS. 5 and 6 illustrate a part of a speaker lA which is a
modified example of the first embodiment of the invention. In the
speaker lA of the modified example illustrated in FIGS. 5 and 6, a
cap member 20A is attached to the opening end portion 11c of the
bobbin 11. The cap member 20A includes the cylindrical portion 22
and the bottom surface portion 23 as the bobbin reinforcement
portion 21 and includes the outer support portion 24 extending from
the opening end portion 11c toward the outer peripheral side.
Further, the cap member 20A includes a support column 26 which is
uprightly formed to the upper side (the side of Z1) from the center
of the bottom surface portion 23, and a plurality of fins 25
extending in the Z1-Z2 direction is arranged regularly in the
circumferential direction between the cylindrical portion 22 and
the support column 26. Since the cap member 20A has high rigidity,
the capability of reinforcing the bobbin 11 is further
improved.
[0044] FIG. 7 is a half cross-sectional view illustrating a part of
a counter drive type speaker 101 which is a second embodiment of
the invention.
[0045] Like the speaker 1 of the first embodiment, in the speaker
101 illustrated in FIG. 7, a direction in which an opening angle of
a cone-shaped vibration plate is less than 180.degree. is an upward
direction and is directed in the Z1 direction.
[0046] In the counter drive type speaker 101, the magnetic circuit
portion 3 is provided at the upper side (the side of Z1) and the
magnetic circuit portion 3 is supported by the frame portion 2. The
magnetic circuit portion 3 includes a pole yoke 4, an upper yoke
5a, and two opposing yokes 6a and 6b. The magnet 7 is fixed between
the pole yoke 4 and the opposing yoke 6a, and the magnetic gap G is
formed in the opposing portion between the yoke 6a and the yoke 6b.
The voice coil 12 is wound on the bobbin 11 at the upper side, and
the voice coil 12 is located inside the magnetic gap G.
[0047] The inner peripheral edge 15b of the vibration plate 15 is
fixed to the outer surface of the bobbin 11, and the inner
peripheral edges 16b of two damper members 16 are also fixed to the
bobbin 11. The outer peripheral edge of the vibration plate 15 and
the outer peripheral edge of the damper member 16 are fixed to the
frame portion 2.
[0048] The cap member 20 is attached to the opening end portion at
the lower side (the side of Z2) of the bobbin 11. The cap member 20
includes the cylindrical portion 22 and the bottom surface portion
23 as the bobbin reinforcement portion 21. The cylindrical portion
22 opposes the inner surface of the bobbin 11 in the vibration
plate fixed portion (i) and the damper member fixed portion (ii),
and the bobbin 11 and the cylindrical portion 22 are fixed to each
other by adhering in at least the vibration plate fixed portion (i)
and the damper member fixed portion (ii).
[0049] While there has been illustrated and described what is at
present contemplated to be preferred embodiments of the present
invention, it will be understood by those skilled in the art that
various changes and modifications may be made, and equivalents may
be substituted for elements thereof without departing from the true
scope of the invention. In addition, many modifications may be made
to adapt a particular situation to the teachings of the invention
without departing from the central scope thereof. Therefore, it is
intended that this invention not be limited to the particular
embodiments disclosed, but that the invention will include all
embodiments falling within the scope of the appended claims.
* * * * *